In outside telephone plant, cable splices must be protected from the effects of the environment in which the cables are used. For example, in splicing a telephone service cable to a distribution cable in new outside telephone plant, particularly in underground installations, protection is afforded by using waterproofed cable together with closures that include provisions for preventing the ingress of moisture.
At the same time, efforts have been and will be made to upgrade existing systems and to rehabilitate deteriorated air-core buried as well as aerial distribution plant, for example, and connecting it to a stable, water-tight plant. These efforts should result in a system which is waterproof throughout, not just in newly added portions, and one which recovers capacity through pairs of conductors that may have been rendered unuseable in the past because of moisture.
Rehabilitation is particularly suited for congested or highly developed areas where costs for new underground cable runs are prohibitively high and where other options such as aerial cable distribution are not feasible, not economical or not acceptable. Such areas characteristically are constructed with single or dual sheath air core cables being spliced in ready access pedestal or pole terminals. In these, a pair of cables extend out of the ground and are spliced together within a pedestal type cabinet or a buried cable may have an exposed end which is spliced to an air core cable at a drop point from an overhead run adjacent a telephone pole. Typically, these splices are above the ground and hence exposed to all the elements.
Problems which have been encountered in these areas which result in increased operating costs are usually a combination of wet cables, faulty buried splices and insulated conductor troubles in pedestals. Symptoms of trouble are manifested in the form of relatively high defective pair counts and in the low number of spare parts which are available for example. Moisture may enter cables through construction damage, subsequent cable jacket cuts, lightning pinholes, or flooding of unplugged ends in pedestals. Conductor troubles in the pedestals themselves are caused by insect damage, cracking of insulation by heat, cracking by exposure to direct sunlight when covers have not been replaced, and repeated craftsperson handling.
Prior art methods of protecting cable splices are disclosed in U.S. Pat. Nos. 2,906,810, 3,934,076 and 4,039,742 in which the spliced cables are assembled to a plug after which the plug and the splice are inserted into a cylindrical capsule which has been prefilled with a waterproofing material to force the waterproofing material around the splice. Not only has it been found that the insertion step sometimes causes the spliced conductors to become disconnected, but the sealant in these kinds of closures tends to leak and when an assembly is inserted into a sealant-filled container, air pockets are created.
A different prior art approach is one shown in U.S. Pat. No. 3,879,574 in which a stiff, resilient, segmented plastic sheet is grooved to reduce its thickness along narrow linear intersecting latticed strips which define rectangular and triangular patterns. This permits the sheet to be cut and folded along selected narrow strips to form hollow enclosures of various sizes and shapes. The sheet section is fastened to itself or necked down at its ends about a cable and secured by tape to provide protection for a cable splice or serve as a mold to shape insulating, self-curing resinous compositions which are applied in liquid form through breakout ports about the splice. The last described arrangement has some drawbacks in that it requires excessive care in the taping of the necked down portions to avoid sealant leakage; moreover, the filling through the breakout ports may not result in a complete fill. Still other arrangements are shown in U.S. Pat. Nos. 3,806,630, 3,920,886 and 4,015,072.
What is needed and what is not provided by the art is a rehabilitation arrangement for outside plant apparatus which makes possible the upgrading of existing splices and plant to integrate them into a waterproofed communications network. Desirably, the arrangement is economical, simple to install and adaptable to a wide range of plant that may be encountered in the field.